1. Field of the Invention
This invention relates to an apparatus for quantitatively extruding food material, typically a plastic food material, and more particularly to an apparatus for supplying a continuous body of food material, uniform in quantity and density throughout the portions of the body, while removing air trapped during the process.
2. Prior Art
U.S. Pat. No. 4,801,258 discloses an apparatus for quantitatively extruding food material. In this apparatus the material is introduced into the space formed between the periphery of a drum and the side wall of a housing. The drum has an inner chamber between its inner wall and the periphery of a cam. A pair of blades is inserted into slits formed on the drum from a compartment in the outside of the drum and a compartment in the inner chamber.
Since the dimensions of the space in the compartment outside of the drum decrease towards the exit port, while the space of the inner chamber increases, the pressure in the outer compartment becomes much higher than that of the inner chamber. Thus the air in the material is drawn out of the outer compartment into the inner chamber via a path formed between the recess on the trailing surface of the blade and the wall of the slit. As a result a cylindrical body of material of a uniform quantity and density, and that has no air entrainment, is extruded from the exit port.
Usually a row of exit ports are provided on a housing for extruding a number of cylindrical bodies of food material. Such exit ports are arranged in the axial direction of the housing. However, when the material clogs one of the exit ports, the material which should be extruded from that exit port moves to and is extruded from its adjacent ports, and thus the quantity of the material extruded from the other exit ports changes. Further, food material such as dough or minced meat tends to clog exit ports. Therefore, in this apparatus of the prior art where the material is extruded from a plurality of exit ports, a uniform supply of food material is not assured.